1. The problem statement, all variables and given/known data Rain falls with velocity of 20m/s parallel to an incline which is at an angle of 37 degrees from the ground. A man starts running down the incline with a velocity 'v' . Find 'v' such that the rain appears to be falling vertically on the man( from his perspective). 2. Relevant equations 3. The attempt at a solution I am confused about the axis i must take. Should i take the x axis on the horizontal of the incline or the ground? I suppose i must resolve the rain into it's rectangular components. But using what angle? Please help.